From 1f44ec75a0023c412898c28582b121b794d83067 Mon Sep 17 00:00:00 2001
From: Arvid Norberg <arvid@libtorrent.org>
Date: Sat, 1 May 2010 17:47:28 +0000
Subject: [PATCH] fixed bug in add_piece() that would trigger asserts

---
 ChangeLog                           | 1 +
 include/libtorrent/piece_picker.hpp | 5 ++++-
 src/piece_picker.cpp                | 8 ++++++--
 src/torrent.cpp                     | 4 +++-
 4 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 9785e615b..7c663aea8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -28,6 +28,7 @@
 	  incoming connection
 	* added more detailed instrumentation of the disk I/O thread
 
+	* fixed bug in add_piece() that would trigger asserts
 	* fixed vs 2010 build
 	* recognizes more clients in identify_client()
 	* fixed bug where trackers wouldn't be retried if they failed
diff --git a/include/libtorrent/piece_picker.hpp b/include/libtorrent/piece_picker.hpp
index c2ea3322e..b354cd3f8 100644
--- a/include/libtorrent/piece_picker.hpp
+++ b/include/libtorrent/piece_picker.hpp
@@ -276,7 +276,10 @@ namespace libtorrent
 		// marks this piece-block as queued for downloading
 		bool mark_as_downloading(piece_block block, void* peer
 			, piece_state_t s);
-		void mark_as_writing(piece_block block, void* peer);
+		// returns true if the block was marked as writing,
+		// and false if the block is already finished or writing
+		bool mark_as_writing(piece_block block, void* peer);
+
 		void mark_as_finished(piece_block block, void* peer);
 		void write_failed(piece_block block);
 		int num_peers(piece_block block) const;
diff --git a/src/piece_picker.cpp b/src/piece_picker.cpp
index 80bb6653f..04a4ccd51 100644
--- a/src/piece_picker.cpp
+++ b/src/piece_picker.cpp
@@ -2089,7 +2089,7 @@ namespace libtorrent
 			*j = i->peer_count + m_seeds;
 	}
 
-	void piece_picker::mark_as_writing(piece_block block, void* peer)
+	bool piece_picker::mark_as_writing(piece_block block, void* peer)
 	{
 #ifdef TORRENT_EXPENSIVE_INVARIANT_CHECKS
 		TORRENT_PIECE_PICKER_INVARIANT_CHECK;
@@ -2133,7 +2133,10 @@ namespace libtorrent
 			info.peer = peer;
 			if (info.state == block_info::state_requested) --i->requested;
 			TORRENT_ASSERT(i->requested >= 0);
-			TORRENT_ASSERT(info.state != block_info::state_writing);
+			if (info.state == block_info::state_writing
+				|| info.state == block_info::state_finished)
+				return false;
+
 			++i->writing;
 			info.state = block_info::state_writing;
 
@@ -2149,6 +2152,7 @@ namespace libtorrent
 			}
 			sort_piece(i);
 		}
+		return true;
 	}
 
 	void piece_picker::write_failed(piece_block block)
diff --git a/src/torrent.cpp b/src/torrent.cpp
index 21ac2c719..e74062792 100644
--- a/src/torrent.cpp
+++ b/src/torrent.cpp
@@ -676,7 +676,9 @@ namespace libtorrent
 		// avoid crash trying to access the picker when there is nont
 		if (is_seed()) return;
 
-		if (picker().have_piece(piece)) return;
+		if (picker().have_piece(piece)
+			&& (flags & torrent::overwrite_existing) == 0)
+			return;
 
 		peer_request p;
 		p.piece = piece;